Attempting to convert a model with "bones" - how to find the coordinates of each rotation point?
With the armature selected switch to Edit Mode, select the bone you want, and the location of the point it rotates around is displayed in the Properties panel (N) under Head:



To automate this open a Text Editor window and run this code:

import bpy

obj = bpy.context.active_object

if obj.mode is not 'OBJECT': bpy.ops.object.set_object_mode()

for bone in obj.data.bones:
    print("Bone: {0} origin is at {1}".format(bone.name, bone.head))


It will output into System Console. You can rewrite it to output to a file in a custom format your engine will understand.

The values will be relative to the armature centre of origin and with Z axis pointing up.